One in three women in the US will give birth by cesarean section. ACOG recognizes that this is a problem, and that many of these cesareans are unnecessary and can be prevented by a change in labor management. I will be reviewing their 2014 Obstetric Care Consensus findings and recommendations in a 2 part series. I will follow that in Part 3 with what the patient can expect from their provider, based on these new recommendations.
ACOG Obstetric Care Consensus: Safe Prevention of the Primary Cesarean Delivery (2014)
One in three women who gave birth in the US in 2011 gave birth by Cesarean Section (c/s). There are certain conditions, such as placenta previa or uterine rupture, where c/s is established as the safest route of delivery. However, for most low risk pregnancies, c/s carries a higher risk of morbidity and mortality (harm and death) for the mother. In one large Canadian study, the, “risk of severe maternal morbidities- defined as hemorrhage that requires hysterectomy or transfusion, uterine rupture, anesthetic complications, shock, cardiac arrest, acute renal failure, assisted ventilation, venous thromboembolism, major infection, or in-hospital wound disruption or hematoma- was increased threefold for cesarean delivery as compared with vaginal delivery (2.7%% vs 0.9%, respectively).” Long term risks of c/s also pose a problem, especially in subsequent pregnancies. The incidence of placenta previa, where the placenta partially or fully covers the cervical opening, increases from 1% with 1 prior c/s, to almost 3% with 3 or more c/s. The risk that the placenta previa will be complicated by placenta accreta (when the placenta attaches too deeply in the uterus) rises to nearly 40% after the 3rd c/s.
Indications for Primary Cesarean
There is a great variation in c/s rates (ranging from 7.1 to 69.9%, and a 15 fold variation among low risk women, from 2.4% to 36.5%) between regions and hospitals. In Illinois in 2010, the average c/s rate was 31.2%. The most common indications for primary c/s (first c/s) included, “in order of frequency, labor dystocia, abnormal or indeterminate (formerly nonreassuring) fetal heart rate tracing, fetal malpresentation, multiple gestation, and suspected fetal macrosomia. Arrest of labor and abnormal or indeterminate fetal heart rate tracing accounted for more than one half of all primary cesarean deliveries.” Safe reductions in primary c/s rates may result from redefining labor dystocia, improved and standardized fetal heart rate interpretation, increasing a woman’s access to nonmedical interventions, performing external cephalic version for breech presentation, and providing a trial of labor for women with twins where twin A is cephalic (head down).
Abnormal First Stage of Labor
Definition of Abnormal First Stage Labor
Labor progression has historically been based on the work by Friedman in the 1950s. The latent phase begins with maternal perception of regular contractions. This has historically been defined as prolonged when lasting >20 hours in a nulliparous woman (no previous births) and <14 hours in a multiparous woman (more than 1 birth). The active phase has been defined as the point at which there is a significant increase in the rate of change of cervical dilation. Based on Friedman’s work, a protracted active phase is considered cervical change of <1.2cm/hr for nulliparous women and <1.5cm/hr for multiparous women. Active phase arrest has been defined as the absence of cervical change for 2 or more hours with adequate uterine contractions and at least 4cm dilation.
Recently, these definitions have been revised based on data from the Consortium on Safe Labor. It has been found that the rate of actual cervical change has been much slower than that described by Friedman. They found that active phase (the time of more rapid cervical change) did not start until at least 6cm. ACOG recommends that the Consortium data be used as the standard, rather than Friedman.
Management of Abnormal First-Stage Labor
Modern researchers have not typically focused on the latent phase of labor, but do find that most women with a prolonged latent phase will eventually progress to active labor with expectant management. Those that do not, will typically either cease contracting, or enter the active phase with amniotomy (rupture of membranes) or pitocin augmentation. Therefore, “a prolonged latent phase (eg. greater than 20 hours in nulliparous women and greater than 14 hours in multiparous women) should not be an indication for cesarean delivery.” In addition, “slow but progressive labor in the first stage of labor should not be an indication for cesarean delivery.” Prolonged first stage has been associated with an increased risk of chorioamnionitis (infection of fetal membranes), but it is difficult to determine if the relationship is causal, or that chorioamnionitis itself results in longer labors. However, “neither chorioamnionitis nor its duration should be an indication for cesarean delivery.”
As long as mother and fetal status are reassuring, “cervical dilation of 6cm should be considered the threshold for the active phase… cesarean delivery for active phase arrest in the first stage of labor should be reserved for women at or beyond 6cm of dilation WITH RUPTURED MEMBRANES [my emphasis] who fail to progress despite 4 hours of adequate uterine activity, or at least 6 hours of oxytocin administration with inadequate uterine activity and no cervical change.”
Abnormal Second Stage of Labor
Definition of Abnormal Second Stage
Second stage begins when the cervix is completely dilated and ends when the baby is delivered. Factors that influence length of second stage include amount of previous deliveries, delayed pushing/laboring down, epidural use, maternal BMI, and fetal position. In nulliparous women, “a longer duration of active pushing was not associated with adverse neonatal outcomes, even in women who pushed longer than 3 hours.” However, this was not the case with multiparous women; when the duration of second stage exceeded 2 or 3 hours, neonatal morbidity was increased. However, the absolute risk of complication was low, and the maximum duration of second stage before a c/s should be performed is unknown.
A longer second stage is associated with increased risk of adverse maternal outcomes (infection, 3rd or 4th degree laceration, and hemorrhage).
Management of Abnormal Second Stage
At least 3 hours of pushing in the nulliparous woman and 2 hours in the multiparous woman should be allowed before diagnosing arrest of second stage. Longer durations may be appropriate as long as progress is being documented and maternal and fetal status are reassuring. If an epidural is used, an additional hour should be added before diagnosis, although the research did not specify if that was time of total second stage with laboring down, or active pushing.
Other Approaches to Reducing Cesareans in the Second Stage
While c/s rates have risen, rates of operative vaginal delivery (vacuum or forceps) have declined significantly. Forceps were associated with a lower risk of seizure, intraventricular hemorrhage, and subdural hemorrhage than vacuum or cesarean, and there was no difference between vacuum delivery and c/s. This shows that operative vaginal delivery can be a safe alternative to c/s, particularly when done on a normal sized baby at a low station, performed by a well trained provider. Operative vaginal delivery is successful in over 97% of cases; less than 3% of women need to deliver by c/s following an attempt.
Fetal malpositioning, such as occiput posterior (“sunny side up”) and occiput transverse, are associated with increased cesarean delivery. Manual rotation of the fetal head, when position has been accurately confirmed and is done by a trained provider, is a reasonable alternative to consider before moving to operative vaginal or cesarean delivery.
Part 2 will discuss the second most common indication for primary c/s, an abnormal fetal heart rate tracing, as well as the effects of induction on c/s rate, and other common indications for primary c/s, such as twin and breech presentation. Part 3 will discuss what the patient can expect from their provider based on these recommendations.